As algae are pumped into the clarifier, they are exposed to ultra violet light that destroys the reproductive ability of single-celled algae. The dead algae are then pumped out of the our Pond Green Free UV Clarifier, where they clump and are removed by your pond's filtration system. Removes heavy algae blooms (usually within 8 days) and keeps the pond algae-free long-term. Tetra Pond Green Free UV Clarifier is durable, easy to conceal and installs in minutes. Comes with a high-efficiency bulb for up to 11 months of continuous operation and a high-clarity quartz glass tube. A viewing window makes it easy to ensure the UV bulb is working. Includes 3/4 inch, 1 inch and 1 1/4 inch ID tubing adapters, as well as a 15 foot power cord. UL Listed. Features a 3-year limited warranty - see product packaging for details. Replacement bulbs available - replace every pond season Available in four sizes: For ponds up to 660 gallons, up to 1,800 gallons, up to 4,400 gallons and up to 8,800 gallons.